The problems associated with statically charged air particles in the vicinity of sensitive manufacturing processes and sensitive workpieces are not new. The build up of static charges on sensitive electronic components may lead to severe damage of those components. The localized static charges themselves may damage or degrade particularly sensitive electronics. More importantly, electrotatic forces on electronics surfaces create an electric field that attracts contaminants carried by the air. Dust particles in the air may be so small that they are little affected by gravity, but rather settleing of the dust particles is brought about by electrostatic forces.
Air ionizing apparatus are well known to dramatically reduce the deposition rate of small dust particles, by propelling ions into the air surrounding a work area to neutralize charged materials present. Partridge U.S. Pat. No. 5,055,963 (issued Oct. 8, 1991) describes a housing with generally open inlet and outlet passages, and a fan and electrodes mounted inside the housing. The fan creates an air flow that pulls room-air through an opening in the back of the housing, and after being ionized the air is propelled out an opening in the front of the housing. Le Vantine U.S. Pat. No. 4,635,161 (issued Jan. 6, 1987) discloses a device having dual air supplies that lead to a positive or negative electrode, and the ionized air is mixed in a vortex chamber. The ionized air is then propelled out the front of the device through small air jets.
Other prior art devices include air ionizing rings where high pressure air is supplied through a small gap in the ring, and flows through the ring past electrodes into the workstation, the air ionizing rings are typically precision machined parts to provide the small gap and surfaces around which the air flows. Shims may be required to control the dimensions of the small gap.
Although such devices as described above have proven generally suitable for their intended purposes, they possess inherent deficiencies which detract from their overall effectiveness in the marketplace. Clean-room environments where electronics manufacturing takes place, have air and lighting coming from overhead. The air is typically delivered throught high efficiency (HEPA) filters that remove contaminants carried in the source air. The devices of the prior art tend to disrupt the air flow from overhead, as well as interfering with the overhead lighting by casting a shadow across the workstation. Devices of the prior art made of metal or having exposed electrodes may be safety hazards, due to electric shock or contact with sharp ends of electrodes. Also, the designs of the prior art do not lend themselves to providing a flow of ionized air across a wide workbench. The devices are not designed to be connected in a modular fashion, to span across an entire workstation. And, the designs of the prior art are not aesthetically appealing and are noisy in operation.